JP2000009592A - Method of measuring interference effect on glass fiber transmission links and transmission system - Google Patents

Method of measuring interference effect on glass fiber transmission links and transmission system

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Publication number
JP2000009592A
JP2000009592A JP11164219A JP16421999A JP2000009592A JP 2000009592 A JP2000009592 A JP 2000009592A JP 11164219 A JP11164219 A JP 11164219A JP 16421999 A JP16421999 A JP 16421999A JP 2000009592 A JP2000009592 A JP 2000009592A
Authority
JP
Japan
Prior art keywords
signals
transmission link
optical
frequency
receiver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP11164219A
Other languages
Japanese (ja)
Inventor
Henning Buelow
ヘニング・ビユーロウ
Harald Schmuck
ハラルト・シユムツク
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Lucent SAS
Original Assignee
Alcatel Alsthom Compagnie Generale dElectricite
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcatel Alsthom Compagnie Generale dElectricite filed Critical Alcatel Alsthom Compagnie Generale dElectricite
Publication of JP2000009592A publication Critical patent/JP2000009592A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/2569—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to polarisation mode dispersion [PMD]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/331—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by using interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/333—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face using modulated input signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/335—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face using two or more input wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/336—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by measuring polarization mode dispersion [PMD]

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Dispersion Chemistry (AREA)
  • Testing Of Optical Devices Or Fibers (AREA)
  • Optical Communication System (AREA)

Abstract

PROBLEM TO BE SOLVED: To simply measure the characteristics (polarization mode dispersion) of a transmitting link by transmitting two signals at different frequencies over the transmission link and evaluating the signals from a frequency corresponding to the frequency difference between these signals. SOLUTION: A light source 1 is connected to a transmission link 7 to receive two signals at different frequencies, i.e., has a laser 2 for generating two optical carriers having a frequency spacing of e.g. 60 GHz by the both side band modulation. At a reception side a photodiode 8 generates electric carriers of 60 GHz by the coherent detection, the polarizing condition of the electric field with two optical carriers varies due to the polarization mode dispersion, hence the power detected by a receiver 9 also varies, resulting in that the power of the carrier frequency of 60 GHz is a measured value showing the polarization mode dispersion over the transmission link 7 and hence the characteristics of a glass fiber link can be analyzed by measuring the instantaneous polarization mode dispersion of the transmission link 7 by a simple measurement.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、独立請求項の一般
分類に従えば、グラスファイバ伝送リンクの干渉効果を
測定する方法及び伝送システムに関する。文献「Ｐｒｏ
ｃｅｅｄｉｎｇｓＩＩ，ＮＯＣ‘９７，Ａｎｔｗｅｒ
ｐ，Ｈ．Ｂｕｌｏｗ，ｐｐ．６５−７２」には、偏波分
散の効果が説明されている。偏波分散は、伝送リンクと
して使用されるグラスファイバの複屈折効果によって生
じる。光信号は偏波状態の速軸及び遅延軸に対応する２
つの成分へ分割され、これら２つの成分は異なった群速
度でグラスファイバ・リンク上を伝送される。２つの信
号成分の異なった群速度は干渉を生じると共に、一般的
な場合、データ情報の乱れを生じる。偏波分散効果は統
計的効果である。なぜなら、グラスファイバの振る舞い
は、それらの温度、歪みの状態、老化の影響によって変
動するからである。偏波分散の変化は、一般的に長期間
に渡って起こる緩慢なプロセスである。従って、伝送リ
ンクに対する偏波分散の影響を絶えず測定する必要はな
い。The present invention relates to a method and a system for measuring the interference effect of a glass fiber transmission link according to the general classification of the independent claims. Document "Pro
seedingsII, NOC'97, Antwer
p, H .; Bulow, pp. 65-72 "describes the effect of polarization dispersion. Polarization dispersion is caused by the birefringence effect of glass fibers used as transmission links. The optical signal corresponds to the fast axis and the delay axis in the polarization state.
The two components are split and these two components are transmitted over the glass fiber link at different group velocities. Different group velocities of the two signal components cause interference and, in the general case, disruption of the data information. The polarization dispersion effect is a statistical effect. This is because the behavior of glass fibers varies depending on their temperature, the state of strain, and the effects of aging. Changes in polarization dispersion are generally slow processes that occur over a long period of time. Therefore, it is not necessary to constantly measure the effect of polarization dispersion on the transmission link.

【０００２】[0002]

【従来の技術】米国特許第５，４７３，４５７号は偏波
分散を測定する方法を開示している。この方法によれ
ば、光信号がファイバを介して伝送され、続いて偏波状
態が偏波コントローラで測定される。次に、信号は偏波
面保存ファイバへ与えられる。次に、光の２つの偏波面
が装置で分離され、コヒーレントに重畳される。信号は
偏波コントローラを較正するために使用される。この方
法では、信号の偏波状態が積極的に影響を受ける。2. Description of the Related Art U.S. Pat. No. 5,473,457 discloses a method for measuring polarization dispersion. According to this method, an optical signal is transmitted through a fiber, and the polarization state is subsequently measured by a polarization controller. Next, the signal is provided to a polarization maintaining fiber. Next, the two polarization planes of the light are separated by the device and superimposed coherently. The signal is used to calibrate the polarization controller. In this method, the polarization state of the signal is positively affected.

【０００３】[0003]

【発明が解決しようとする課題】対照的に、偏波分散に
よって生じた干渉効果を測定する本発明の方法は、独立
請求項の特徴に従えば、２つの周波数バンドを含む出力
信号をコヒーレント受信器で測定するだけで、後の分析
に使用することのできる有効測定値を得ることができる
という利点を有する。この方法は偏波コントローラ、偏
波測定器、及び偏波面保存ファイバの使用を全く不要に
する。これらはすべて複雑性とコストを大きくする光学
コンポーネントである。本発明に従った方法は、純粋に
電気的な手段を用いて伝送リンクの特性を簡単に測定で
きるようにする。In contrast, the method according to the invention for measuring the interference effect caused by polarization dispersion comprises, according to the features of the independent claims, coherent reception of an output signal comprising two frequency bands. This has the advantage that an effective measurement can be obtained which can be used for subsequent analysis only by measuring with a measuring instrument. This method eliminates the need for a polarization controller, polarimeter, and polarization maintaining fiber at all. These are all optical components that add complexity and cost. The method according to the invention makes it possible to simply measure the characteristics of the transmission link using purely electrical means.

【０００４】従属請求項に記載された手順は、独立請求
項に限定された方法の実施形態及び改善を更に利点ある
ものにする。この測定方法及び高周波数、例えば６０Ｇ
Ｈｚを使用すれば、コヒーレント測定方法により受信器
でＰＭＤを決定することができる。有利なことに、偏波
分散は、伝送リンク特性の緩慢な変化に関連しているの
で、本発明の方法は伝送期間の全体に渡って使用される
ことはない。従って、測定ユニットとして少なくとも時
々に側波帯変調信号を発生し、測定用に評価することの
できる信号を与えるただ１つの変調器を使用するのが有
利である。[0004] The measures described in the dependent claims make the method embodiments and improvements defined in the independent claims even more advantageous. This measurement method and high frequency, for example, 60G
Using Hz, the PMD can be determined at the receiver by a coherent measurement method. Advantageously, the method of the present invention is not used throughout the transmission period, since polarization dispersion is associated with slow changes in transmission link characteristics. It is therefore advantageous to use as a measuring unit only one modulator which at least occasionally generates a sideband modulation signal and provides a signal which can be evaluated for measurement.

【０００５】本発明の方法の他の利点は、それがオンラ
インで使用できることであり、従って、統計的記録と分
析のために側波帯変調信号を継続的に伝送することを可
能にすることである。Another advantage of the method of the present invention is that it can be used on-line, thus allowing the continuous transmission of sideband modulated signals for statistical recording and analysis. is there.

【０００６】[0006]

【課題を解決するための手段】本発明に従った伝送シス
テムは光送信器、伝送リンク、及び光受信器を含み、利
点としては、第１の変調器が測定信号用の側波帯を発生
し、第２の変調器がデータ用の信号を処理する。他の有
利な実施形態は、側波帯を発生すると共にデータを変調
する１つの変調器を使用する。SUMMARY OF THE INVENTION A transmission system according to the present invention includes an optical transmitter, a transmission link, and an optical receiver, with the advantage that the first modulator generates a sideband for a measurement signal. Then, the second modulator processes the signal for data. Another advantageous embodiment uses a single modulator that generates sidebands and modulates data.

【０００７】本発明の実施形態の例は図面に示されると
共に、以下の説明で詳細に記述される。[0007] Examples of embodiments of the present invention are shown in the drawings and are described in detail in the following description.

【０００８】[0008]

【発明の実施の形態】図１は本発明に従った伝送システ
ムを示す。光送信器（１）は伝送リンク（７）に接続さ
れる。光送信器（１）の中にはレーザ（２）が置かれ、
その出力は変調器（３）の入力へ接続される。変調器
（３）は他の入力を有し、その入力は外部発振器（５）
へ接続される。入力側の変調器（３）の出力は光増幅器
（４）へ結合され、その出力は伝送リンク（７）へ接続
される。伝送リンク（７）の端部には、可能性として電
気増幅器を有するフォトダイオード（８）が置かれ、前
記フォトダイオードの出力はＰＣ（９）へ接続される。
光学光源（１）は、両側波帯変調によって６０ ＧＨｚ
の周波数間隔を有する２つの光学キャリヤを発生するレ
ーザ（２）である。図１の６を参照されたい。受信器側
では、コヒーレント検波によって、フォトダイオード
（８）の上に６０ＧＨｚの電気キャリヤが発生される。
図１の１０を参照されたい。６０ＧＨｚのこのキャリヤ
のパワーは、２つの光学キャリヤの偏波状態、更に正確
には２つの電界のスカラー積の関数である。偏波分散に
よって、２つの光学キャリヤにおける電界の偏波状態は
変化する。従って、受信器（９）で検出される電力も変
化する。その結果、６０ＧＨｚのキャリヤ周波数の検出
されたパワーは、伝送リンクにおける偏波分散の変化を
示す測定値となる。この簡単な測定によって、伝送リン
クの瞬時の偏波分散を検出し、グラスファイバ・リンク
の統計的振る舞いを分析することができる。測定された
パワーはＰＣ（９）によって評価され、処理される。こ
の測定方法によって、ＭＨｚを超える周波数を変化させ
て偏波分散の変化を時間的に記録することができる。偏
波分散の値を知ることによって、それを積極的に受信器
中の補償回路に使用することができる。FIG. 1 shows a transmission system according to the invention. The optical transmitter (1) is connected to a transmission link (7). A laser (2) is placed in the optical transmitter (1),
Its output is connected to the input of modulator (3). The modulator (3) has another input, whose input is an external oscillator (5).
Connected to The output of the modulator (3) on the input side is coupled to an optical amplifier (4), whose output is connected to a transmission link (7). At the end of the transmission link (7) is located a photodiode (8), possibly with an electric amplifier, the output of which is connected to a PC (9).
The optical light source (1) is 60 GHz by double sideband modulation.
(2) generating two optical carriers having a frequency spacing of Please refer to FIG. On the receiver side, a coherent detection generates a 60 GHz electrical carrier on the photodiode (8).
See 10 in FIG. The power of this carrier at 60 GHz is a function of the polarization state of the two optical carriers, more precisely the scalar product of the two electric fields. The polarization state changes the polarization state of the electric field at the two optical carriers. Therefore, the power detected by the receiver (9) also changes. As a result, the detected power at the carrier frequency of 60 GHz is a measurement that indicates a change in polarization dispersion on the transmission link. With this simple measurement, the instantaneous polarization dispersion of the transmission link can be detected and the statistical behavior of the glass fiber link analyzed. The measured power is evaluated and processed by the PC (9). According to this measurement method, a change in polarization dispersion can be temporally recorded by changing a frequency exceeding MHz. Knowing the value of the polarization dispersion allows it to be actively used in the compensation circuit in the receiver.

【０００９】測定の前提条件は、周波数ｆで分離された
２つのバンドを使用することである。これらのバンドは
等しく偏波されるか等しいパワーを有する必要はない。
これが、光学光源として２つのレーザを使用できる理由
である。２つのバンドがどのようにして発生されるかは
重要ではない。ＰＭＤ効果の解像度は周波数が高ければ
良好になるから、バンド間の周波数間隔のみに意味があ
る。A prerequisite for the measurement is to use two bands separated by a frequency f. These bands need not be equally polarized or have equal power.
This is why two lasers can be used as optical light sources. It is not important how the two bands are generated. The higher the frequency, the better the resolution of the PMD effect, so only the frequency spacing between bands is significant.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明に従った伝送システムを示す図である。FIG. 1 shows a transmission system according to the invention.

【符号の説明】[Explanation of symbols]

１ 光送信器 ２ レーザ ３ 変調器 ４ 光増幅器 ５ 外部発振器 ７ 伝送リンク ８ フォトダイオード ９ ＰＣ Reference Signs List 1 optical transmitter 2 laser 3 modulator 4 optical amplifier 5 external oscillator 7 transmission link 8 photodiode 9 PC

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 偏波分散によって生じたグラスファイバ
伝送リンク（７）上の干渉効果を測定する方法であっ
て、光学光源（１）から異なった周波数の２つの信号を
伝送リンク（７）へ与え、これらの信号を伝送し、コヒ
ーレント受信器（８）で、これら信号の周波数の差に対
応する周波数（ｆ）で信号を評価することを特徴とす
る、グラスファイバ伝送リンクの干渉効果測定方法。A method for measuring the interference effect on a glass fiber transmission link (7) caused by polarization dispersion, wherein two signals of different frequencies are transmitted from an optical light source (1) to a transmission link (7). And transmitting the signals and evaluating the signals at a frequency (f) corresponding to the difference between the frequencies of the signals with a coherent receiver (8). . 【請求項２】 光学光源（１）から側波帯変調信号
（６）を与え、その信号を伝送リンク（７）へ送り込ん
で伝送し、コヒーレント受信器（８）で、側波帯変調信
号（６）の変調周波数に対応する周波数（ｆ）でその信
号を評価することを特徴とする、請求項１に記載のグラ
スファイバ伝送リンクの干渉効果測定方法。2. A sideband modulated signal (6) is provided from an optical light source (1) and transmitted to a transmission link (7) for transmission and transmitted by a coherent receiver (8) to a sideband modulated signal (6). 2. The method according to claim 1, wherein the signal is evaluated at a frequency (f) corresponding to the modulation frequency of (6). 【請求項３】 光学光源（１）が２つの独立した光源を
含むことを特徴とする、請求項１に記載のグラスファイ
バ伝送リンクの干渉効果測定方法。3. The method according to claim 1, wherein the optical light source comprises two independent light sources. 【請求項４】 少なくとも１つの変調器（３）に接続さ
れた光送信器（１）と、伝送リンク（７）と、及び受信
器（８）とを用いてデータを伝送する方法であって、光
送信器（１）によって２つの信号を少なくとも時々に発
生し、コヒーレント受信器（８）で、それら信号間の間
隔に対応する周波数でそれら信号を評価し、測定されて
コヒーレントに重畳された信号の測定パワーを、全伝送
システムの較正に使用することを特徴とするデータの伝
送方法。4. A method for transmitting data using an optical transmitter (1) connected to at least one modulator (3), a transmission link (7) and a receiver (8). , Two signals are generated at least from time to time by the optical transmitter (1) and the coherent receiver (8) evaluates the signals at a frequency corresponding to the spacing between them, and is measured and coherently superimposed. A method for transmitting data, wherein the measured power of the signal is used for calibrating the entire transmission system. 【請求項５】 周波数の異なる２つの信号を継続的に伝
送することを特徴とする、請求項３に記載のグラスファ
イバ伝送リンクの干渉効果測定方法。5. The method according to claim 3, wherein two signals having different frequencies are continuously transmitted. 【請求項６】 光送信器（１）と、伝送リンク（７）
と、光受信器（８）とを含む伝送システムであって、光
送信器が、側波帯を発生する第１の変調器（３）とデー
タとを変調する第２の変調器を有することを特徴とす
る、伝送システム。6. An optical transmitter (1) and a transmission link (7).
And a light receiver (8), wherein the light transmitter has a first modulator (3) for generating sidebands and a second modulator for modulating data. A transmission system. 【請求項７】 光送信器（１）と、伝送リンク（７）
と、光受信器（８）とを含む伝送システムであって、光
送信器（１）が、側波帯を発生すると共にデータを変調
する１つの変調器を有することを特徴とする伝送システ
ム。7. An optical transmitter (1) and a transmission link (7).
And a light receiver (8), wherein the light transmitter (1) has one modulator for generating sidebands and modulating data. 【請求項８】 光送信器（１）と、伝送リンク（７）
と、及び光受信器（８）とを含む伝送システムであっ
て、光送信器が、２つの周波数バンドを発生する源とし
て２つのレーザを有することを特徴とする伝送システ
ム。8. An optical transmitter (1) and a transmission link (7).
And an optical receiver (8), wherein the optical transmitter has two lasers as sources for generating two frequency bands.
JP11164219A 1998-06-20 1999-06-10 Method of measuring interference effect on glass fiber transmission links and transmission system Pending JP2000009592A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19827638A DE19827638A1 (en) 1998-06-20 1998-06-20 Method for measuring interference effects on fiber optic transmission links and transmission system
DE19827638.9 1998-06-20

Publications (1)

Publication Number Publication Date
JP2000009592A true JP2000009592A (en) 2000-01-14

Family

ID=7871580

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CA2275823A1 (en) 1999-12-20

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